A Physics Based Model with an Ankle/Hip Controller for Predicting Motion Induced Interruptions

Abstract

Ship motions can greatly impact a person's ability to perform their duties at sea. One metric that can be used to measure this is called a Motion Induced Interruption (MII). An MII occurs when a person stops performing their task to readjust their balance or brace themselves against falling. An increase in the number of MIIs encountered will decrease safety and efficiency of a ship and its crew. This thesis presents a physics based model that can predict MIIs in both the sagittal and frontal planes. It uses a Reaction Mass Pendulum (RMP) model derived from an inverted pendulum. To validate the MIIs predicted by the RMP model, motion capture data from a recent sea trial was used. The trial data provided the actual MII times for eight sailors and these MII times were compared to values predicted by the RMP model.